The purpose of the proposed research is to establish the feasibility of a novel plethysmographic approach to the determination of human body volume and composition. The need for a practical, accurate, non-invasive and low cost device for the measurement of body composition is well established for the general population, where excess body fat is associated with many disease processes, e.g., cardiovascular disease, diabetes, and pulmonary disease. Also important is the assessment of body composition and nutritional status of normal and low birth weight infants, for whom caloric reserves are critical. A whole body plethysmograph is used to determine body volume and subsequent body density. The volume of air in the chamber is perturbed by a small loudspeaker, and the spectral energy of the resulting pressure change is analyzed. The procedure is entirely comfortable and minimal patient compliance is required. Based on demonstration of technical feasibility, the proposed research will lead to development of a new method of body composition determination that will be highly attractive for commercial application. Commercial application will be found in the general population where the trend towards modification of controllable risk factors is now well established. Medical applications would include health care of low birth weight infants, patients with eating disorders, and the obese.